US7654375B2 - Rotation transmission device - Google Patents

Rotation transmission device Download PDF

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Publication number
US7654375B2
US7654375B2 US10/591,160 US59116005A US7654375B2 US 7654375 B2 US7654375 B2 US 7654375B2 US 59116005 A US59116005 A US 59116005A US 7654375 B2 US7654375 B2 US 7654375B2
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United States
Prior art keywords
electromagnetic coil
outer ring
transmission device
rotation transmission
revolving speed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related, expires
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US10/591,160
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English (en)
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US20070170029A1 (en
Inventor
Koichi Okada
Takahide Saito
Hiroshi Bunko
Tetsuya Yamamoto
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NTN Corp
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NTN Corp
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Publication date
Priority claimed from JP2004057567A external-priority patent/JP4545457B2/ja
Priority claimed from JP2004195769A external-priority patent/JP4824288B2/ja
Application filed by NTN Corp filed Critical NTN Corp
Assigned to NTN CORPORATION reassignment NTN CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: YAMAMOTO, TETSUYA, SAITO, TAKEHIDE, BUNKO, HIROSHI, OKADA, KOICHI
Publication of US20070170029A1 publication Critical patent/US20070170029A1/en
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Publication of US7654375B2 publication Critical patent/US7654375B2/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D41/00—Freewheels or freewheel clutches
    • F16D41/06—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface
    • F16D41/08—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface with provision for altering the freewheeling action
    • F16D41/086—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface with provision for altering the freewheeling action the intermediate members being of circular cross-section and wedging by rolling
    • F16D41/088—Freewheels or freewheel clutches with intermediate wedging coupling members between an inner and an outer surface with provision for altering the freewheeling action the intermediate members being of circular cross-section and wedging by rolling the intermediate members being of only one size and wedging by a movement not having an axial component, between inner and outer races, one of which is cylindrical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D27/00—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor
    • F16D27/10—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor with an electromagnet not rotating with a clutching member, i.e. without collecting rings
    • F16D27/108—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor with an electromagnet not rotating with a clutching member, i.e. without collecting rings with axially movable clutching members
    • F16D27/112—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor with an electromagnet not rotating with a clutching member, i.e. without collecting rings with axially movable clutching members with flat friction surfaces, e.g. discs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D48/00—External control of clutches
    • F16D48/06—Control by electric or electronic means, e.g. of fluid pressure
    • F16D48/064—Control of electrically or electromagnetically actuated clutches
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D27/00—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor
    • F16D2027/002—Electric or electronic circuits relating to actuation of electromagnetic clutches
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D27/00—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor
    • F16D2027/005—Details relating to the internal construction of coils or to clutches having more than one coil in the same housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D27/00—Magnetically- or electrically- actuated clutches; Control or electric circuits therefor
    • F16D2027/008—Details relating to the magnetic circuit, or to the shape of the clutch parts to achieve a certain magnetic path
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/10—System to be controlled
    • F16D2500/102—Actuator
    • F16D2500/1021—Electrical type
    • F16D2500/1022—Electromagnet
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/10—System to be controlled
    • F16D2500/104—Clutch
    • F16D2500/10443—Clutch type
    • F16D2500/1045—Friction clutch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/30—Signal inputs
    • F16D2500/304—Signal inputs from the clutch
    • F16D2500/3041—Signal inputs from the clutch from the input shaft
    • F16D2500/30415—Speed of the input shaft
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/50—Problem to be solved by the control system
    • F16D2500/501—Relating the actuator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/70—Details about the implementation of the control system
    • F16D2500/704—Output parameters from the control unit; Target parameters to be controlled
    • F16D2500/70402—Actuator parameters
    • F16D2500/70418—Current

Definitions

  • This invention relates to a rotation transmission device mounted on a rotary shaft in e.g. a vehicle drivetrain for selectively transmitting the torque of the rotary shaft to another element.
  • Such rotation transmission devices include a two-way clutch type rotation transmission device comprising a roller clutch including an inner member, an outer ring and rollers disposed between the inner member and the outer ring, and an electromagnetic clutch. Torque is selectively transmitted between the inner member and the outer ring by selectively energizing the electromagnetic clutch and thus engaging the roller clutch. It is desired that the electromagnetic clutch consume less energy and produce less heat. It is also desirable that the electromagnetic clutch function as a heater in a low temperature environment.
  • Patent document 1 which is titled “Method for controlling a rotation transmission device” proposes a rotation transmission device which satisfies these requirements.
  • Patent document 1 proposes to save energy and reduce heat build-up by intermittently applying current to the electromagnetic coil to keep the two-way clutch engaged, thereby keeping the vehicle in its 4WD mode.
  • Current applied to the electromagnetic coil is controlled by pulse width modulation (PWM).
  • PWM pulse width modulation
  • the two-way clutch of Patent publication 1 is mounted in a transfer case of a 4WD vehicle of the front-engine, rear-drive layout. But such two-way clutches can be used for various other devices.
  • Patent document 2 discloses a method for controlling a 4WD vehicle using a rotation transmission device similar to the one disclosed in Patent publication 1.
  • this control method if 2WD mode is selected while the ambient temperature is low and thus the oil temperature in the transfer case, as detected by a temperature sensor, is lower than a predetermined value, hub clutches or a front axle engaging means is locked to prevent vibrations of the vehicle due to repeated locking and unlocking of the two-way roller clutch.
  • Patent document 2 discloses that the electromagnetic coil can be used as a heater by applying current to the electromagnetic coil while the ambient temperature is low. Irrespectively of whether the vehicle is traveling or at a stop, simply by energizing the electromagnetic coil, the coil can be used as a heater to heat lubricating oil and thus to instantly reduce its viscous resistance. But when the electromagnetic coil is energized, the coil also produces magnetic attraction force as an electromagnet. Thus, if a large current is applied to produce high calorie heat, the armature may be attracted to the rotor, causing untimely locking of the roller clutch. It is therefore desired to determine the current to be applied to the electromagnetic coil to an optimum value and to provide an electromagnet which can be used as a heater in a low-temperature environment without the possibility of untimely and undesired locking of the roller clutch.
  • the output member has a large axial length. Further, because a nonmagnetic rotor guide is fitted in the output member so as not to be rotatable relative to the output member, and the rotor is fitted in the rotor guide to prevent leakage of the magnetic flux that flows through the rotor, the output member has a large diameter too. The entire rotation transmission device is thus heavyweight.
  • Patent document 3 proposes to divide the output member into an outer ring and an outer member made of a nonmagnetic material such as synthetic resin and rotationally fixed to the outer ring, provide the two-way clutch between the outer ring and the input member and support the rotor of the electromagnetic clutch on the outer member.
  • the rotation transmission device disclosed in Patent document 3 uses a coupling means for coupling the outer ring to the outer member, such coupling means comprising a radial pin through which the outer ring and the outer member are coupled together so as to be nonrotatable and axially immovable relative to each other, or comprising flat surfaces of the outer ring and the outer member that abut each other, thereby preventing relative rotation between the outer ring and the outer member, and a snap ring engaged in a ring groove formed in the outer periphery of the outer ring to prevent axial movement of the outer member relative to the outer ring.
  • coupling means comprising a radial pin through which the outer ring and the outer member are coupled together so as to be nonrotatable and axially immovable relative to each other, or comprising flat surfaces of the outer ring and the outer member that abut each other, thereby preventing relative rotation between the outer ring and the outer member, and a snap ring engaged in a ring groove formed in the outer peripher
  • Patent document 1 JP patent publication 11-159545A
  • Patent document 2 JP patent publication 11-157355A
  • Patent document 3 JP patent publication 2001-311438A
  • An object of the present invention is to provide a control system which can variably apply current to the electromagnetic coil of a rotation transmission device, and thereby selectively engage the roller clutch of the rotation transmission device under the magnetic force produced by the electromagnetic coil.
  • Another object of the invention is to provide a rotation transmission device of which the electromagnetic coil is controlled based on the revolving speed of the rotary shaft to reduce power consumption and the size of the electromagnetic coil.
  • Still another object of the invention is to provide a rotation transmission device in which the output member is divided into an outer ring and a nonmagnetic cover, a two-way clutch is mounted between the outer ring and the input member, and an electromagnetic clutch for controlling the two-way clutch is mounted between the cover and the input member, and wherein the cover is coupled to the outer ring with high reliability.
  • a control system for a rotation transmission device comprising a rotation transmission device comprising a roller clutch unit including an inner member, an outer ring and rollers as engaging elements disposed between the inner member and the outer ring for selectively transmitting torque of a rotary shaft, and an electromagnetic clutch unit including an electromagnetic coil for selectively engaging and disengaging the roller clutch unit by electromagnetic force produced by the electromagnetic coil; a variable setting unit for variably applying current to the electromagnetic coil corresponding to the relative speed between the inner member and the outer ring when the roller clutch unit engages; and a control unit for controlling the variable setting unit.
  • a rotation transmission device comprising a roller clutch unit including an inner member, an outer ring and rollers as engaging elements disposed between the inner member and the outer ring for selectively transmitting torque of a rotary shaft, and an electromagnetic clutch unit including an electromagnetic coil for selectively engaging and disengaging the roller clutch unit by electromagnetic force produced by the electromagnetic coil, wherein when the roller clutch unit engages, a rated current corresponding to a rated revolving speed which is approximately a revolving speed of the rotary shaft when the electromagnetic coil is activated most frequently is applied to the electromagnetic coil, and wherein when the roller clutch unit engages, electric power is applied to the electromagnetic coil according to the relative revolving speed between the inner member and the outer ring so that the roller clutch is engageable by a current corresponding to the relative revolving speed.
  • the attraction force produced by the electromagnetic clutch is required to be only slightly greater than the force for keeping the clutch in the neutral position.
  • a current larger than the minimum current necessary to keep the clutch engaged is preferably applied to the electromagnetic clutch to engage the roller clutch.
  • a current that is greater than a reference current necessary to keep the roller clutch unit engaged by a factor of n which is greater than 1 is preferably applied to the electromagnetic coil.
  • the current applied to the electromagnetic clutch is increased or reduced according to the revolving speed of the rotary shaft and depending upon whether the clutch is of the inner cam type or the outer cam type. Once the roller clutch engages, the current applied is reduced to the reference current.
  • the reference current is also adjusted according to the revolving speed of the rotary shaft and depending upon whether the clutch is of the inner cam type or the outer cam type.
  • the applied current is controlled by applying a control signal from the control unit to the variable setting unit of the control system for the rotation transmission device.
  • the input and output shafts are provided with rotation sensors. But if there are rotation sensors provided for a different purpose, the signal therefrom may be sent to the control unit to detect the revolving speed. Based on the thus detected revolving speed, the control unit applies a control signal to the variable setting unit to variably apply current to the electromagnetic coil.
  • variable setting unit increases the applied current if the clutch is of the outer cam type and reduces the applied current if the clutch is of the inner cam type with an increase in the revolving speed.
  • the variable setting unit applies a current that is greater than the reference current by a factor of n.
  • n (>1) should be increased.
  • the applied current is reduced to the reference current.
  • the reference current is also adjusted according to the revolving speed of the rotary shaft and depending upon whether the clutch is of the inner cam type or the outer cam type.
  • a rotation transmission device wherein the cam surfaces are formed on an outer periphery of a large-diameter portion of the inner member, wherein the raceway is a cylindrical surface formed on the inner periphery of the outer ring, the cam surfaces and the cylindrical surface defining wedge-shaped spaces therebetween,
  • the electromagnetic clutch unit including a rotor guide through which the rotor is coupled to the outer ring, the rotor guide being a nonmagnetic cover provided separately from the outer ring, wherein a protrusion is formed on one of opposed end surfaces of the outer ring and the cover and is engaged in a cutout formed in the other of the opposed end surfaces, and wherein a coupling means is provided radially inwardly of the portion where the protrusion engages in the cutout for axially inseparably coupling the cover to the outer ring.
  • the coupling means may comprise ring grooves formed in the inner periphery of the outer ring at an open end thereof and an inner periphery of the protrusion, and a radially elastically deformable snap ring engaged in the ring grooves.
  • a discharge hole for lubricating oil is preferably defined between axially opposed end surfaces of the cutout and the protrusion to eliminate the need to form a separate oil discharge hole later and thus to reduce the cost.
  • arcuate slits defining a circle are formed in a surface of the rotor opposed to and adapted to be attracted to the armature, and nonmagnetic elastic members are each received in one of the slits so as to protrude from the surface of the rotor. This prevents entry of foreign matter into the device through the slits, and also eliminates the need to separately provide a separation spring for biasing the armature away from the rotor.
  • the rotation transmission device can thus be assembled more easily.
  • a seal is preferably provided radially inwardly of the rotor to prevent entry of foreign matter.
  • the retainer for retaining the engaging elements is rotatably supported on a plate which is fitted on the input member and axially immovably fixed to the input member by a snap ring
  • the snap ring may separate under centrifugal force while the input member is rotating at high speed, thus making it impossible to axially retain the plate.
  • the retainer has its inner periphery supported at its end on an outer periphery of a snap ring engaged in a ring groove formed in the outer periphery of the input member.
  • the switch spring is received in a recess formed in an end surface of the large-diameter portion. If the switch spring comes out of the recess, it cannot perform its expected function.
  • a ring groove is formed in the radially inner surface of the radially outer wall of the recess, and the switch spring is mounted in the ring groove.
  • the outer ring is preferably rotatably supported on the inner member through a bearing fitted in a bearing fitting surface formed on the inner periphery of the outer ring and having the same diameter as the cylindrical surface.
  • control system for controlling the rotation transmission device including the roller clutch unit for selectively transmitting rotation through rollers, and the electromagnetic clutch unit for controlling the roller clutch unit with the electromagnetic force produced by the electromagnetic coil
  • control system comprising the variable setting unit for variably applying current to the electromagnetic coil, and the control unit for controlling the variable setting unit, it is possible to variably apply current corresponding to the revolving speed of the rotary shaft to the electromagnetic coil, reduce power consumption of the rotation transmission device and variably determine the applied current.
  • the rotation transmission device comprises the roller clutch unit for selectively transmitting rotation through rollers, and the electromagnetic clutch unit for controlling the roller clutch unit with the electromagnetic force produced by the electromagnetic coil, wherein rated current corresponding to the rated revolving speed corresponding to the frequency of use can be applied to the electromagnetic coil, and current is variably applied to the electromagnetic coil according to the revolving speed of the rotary shaft.
  • a protrusion is formed on one of opposed end surfaces of the outer ring and the cover and is engaged in a cutout formed in the other of the opposed end surfaces.
  • the cover can thus be rotationally fixed to the outer ring.
  • FIG. 1 is a sectional view of a rotation transmission device of the inner cam type according to a first embodiment of the present invention
  • FIGS. 2A and 2B are sectional views taken along lines IIa-IIa and IIb-IIb of FIG. 1 , respectively;
  • FIG. 3 is a sectional view of a rotation transmission device of the outer cam type according to a second embodiment of the present invention.
  • FIG. 4 is a sectional view taken along line IV-IV of FIG. 3 ;
  • FIG. 5 is a block diagram of a control circuit for a rotation transmission device
  • FIG. 6A shows how the rotation transmission device of the first embodiment is controlled (shows the relationship between the revolving speed of the cam ring of the inner cam type and the current applied to the electromagnetic coil);
  • FIG. 6B shows how the rotation transmission device of the first embodiment is controlled (shows the relationship between the clearance between the rotor and the armature and the attraction force necessary to engage the clutch with revolving speeds N X , N Y and N Z of the cam ring of the inner cam type as parameters);
  • FIG. 7A shows how the rotation transmission device of the second embodiment is controlled (shows the relationship between the revolving speed of the outer ring of the outer cam type and the current applied to the electromagnetic coil);
  • FIG. 7B shows how the rotation transmission device of the second embodiment is controlled (shows the relationship between the clearance between the rotor and the armature and the attraction force necessary to engage the clutch with revolving speeds N X , N Y and N Z of the outer ring of the outer cam type as parameters);
  • FIG. 8A shows how the rotation transmission device of the second embodiment is controlled (shows the relationship between the revolving speed N of the outer ring of the outer cam type, current and time);
  • FIG. 8B shows how the device of FIG. 3 is controlled at a rated revolving speed N 0 (shows the relationship between the revolving speed N of the outer ring of the outer cam type, current and time);
  • FIG. 9 shows the relationship between the frequency of use of the clutch and the revolving speed
  • FIGS. 10A and 10B schematically show a mode switching circuit of the electromagnetic coil
  • FIG. 11 is a vertical sectional front view of a rotation transmission device according to a third embodiment of the present invention.
  • FIG. 12 is a sectional view taken along line II-II of FIG. 11 ;
  • FIG. 13 is a sectional view taken along line III-III of FIG. 11 ;
  • FIG. 14 is an enlarged sectional view of the device of FIG. 11 , showing its electromagnetic clutch unit;
  • FIG. 15 is a sectional view of a different electromagnetic clutch
  • FIG. 16 is an exploded perspective view of an output member and a cover of the rotation transmission device of FIG. 11 ;
  • FIG. 17 is a sectional view of a different discharge hole of the rotation transmission device of FIG. 11 ;
  • FIG. 18 is a sectional view of a yet another discharge hole of the rotation transmission device of FIG. 11 .
  • FIG. 1 is a partial sectional view of the rotation transmission device of the first embodiment.
  • cam surfaces are formed on the outer periphery of an inner member.
  • the rotation transmission device C 1 of this embodiment comprises a roller clutch unit 10 (two-way clutch) including a plurality of rollers 13 as engaging elements each received in one of pockets 17 formed in a retainer 12 so as to be circumferentially spaced apart from each other for transmitting torque from the inner member 11 , which is provided at one end of the input shaft 1 x , to an outer ring 14 provided at one end of an output shaft 5 x , and an electromagnetic clutch unit 20 as an electromagnetic control means for electromagnetically engaging and disengaging the rollers 13 of the clutch unit 10 .
  • a roller clutch unit 10 two-way clutch
  • the electromagnetic clutch unit 20 rotates the retainer 12 relative to the inner member 11 by selectively bringing an armature 23 into and out of frictional contact with a rotor 22 , thereby selectively engaging and disengaging the rollers 13 .
  • the inner member 11 at the end of the input shaft 1 x is disposed radially inwardly of and coaxially with the outer ring 14 .
  • the input shaft 1 x , the output shaft 5 x and other members of the roller clutch unit are supported by bearings 2 , 3 and 4 so as to be rotatable relative to each other.
  • Cam surfaces 15 are formed on the outer periphery of the inner member 11 .
  • a raceway 16 is formed on the inner periphery of the outer ring 14 .
  • the retainer 12 is disposed therebetween.
  • the rollers 13 which are each received in one of the pockets 17 , are disposed each on one of the cam surfaces 15 so as to be circumferentially equidistantly spaced apart from each other.
  • each roller 13 By pushing the rollers 13 into respective wedge spaces defined by the cam surfaces 15 and the raceway 16 , the clutch engages.
  • the retainer 12 is elastically held in a neutral position relative to the inner member 11 where each roller 13 is disposed substantially at the center of the corresponding cam surface 15 by means of a switch spring 18 .
  • the electromagnetic clutch unit is provided around the input shaft 1 x so as to be disposed axially outwardly of and adjacent to the outer ring 14 of the roller clutch unit 10 .
  • the electromagnetic coil 21 is surrounded by a yoke 21 a and fixed to a stationary member through a support member Sp.
  • the rotor 22 and its rotor guide 22 g surround the electromagnetic coil 21 .
  • the rotor 22 has a flange 22 a disposed between the electromagnetic coil 21 and the armature 23 .
  • the rotor 22 is fixed to the rotor guide 22 g , which is in turn fixed to the end surface of the outer ring 14 .
  • the rotor 22 comprises a radially outer cylindrical portion and a radially inner cylindrical portion 22 b which is rotatably supported on the input shaft 1 x through the bearing 3 and connected to the radially outer cylindrical portion through the flange 22 a .
  • the rotor has therefore a U-shaped longitudinal section. Electric power is supplied to the electromagnetic coil through a power supply line Lc.
  • the armature 23 has holes (not shown) in which axial projections formed on the end surface of the retainer 12 are inserted, respectively, so as to be axially movable but rotationally fixed relative to the retainer 12 .
  • the switch spring 18 is disposed between the opposed end surfaces of the armature 23 and the inner member 11 to bias the rollers 13 each toward the center of one of the cam surfaces.
  • the switch spring 18 is a ring-shaped elastic member and is received in a groove 11 a defined by a shoulder formed on the inner member 11 .
  • the switch spring 18 has radially outwardly bent end portions 18 a that are received in a cutout 11 c formed in the wall defining the groove 11 a (at its upper portion in FIG. 2B ) and a cutout 12 c formed in the retainer, thereby biasing the retainer toward the position where the cutouts 11 c and 12 c radially align with each other.
  • FIGS. 3 and 4 show the rotation transmission device C 2 of the second embodiment.
  • cam surfaces are formed on the inner periphery of the outer ring.
  • Elements identical to those of the first embodiment are denoted by identical numerals and their description is omitted.
  • the rotation transmission device C 2 comprises a roller clutch unit 10 and an electromagnetic clutch unit 20 .
  • the electromagnetic clutch unit 20 is provided axially outwardly of and adjacent to the outer ring of the roller clutch unit 10 .
  • the roller clutch unit 10 includes an inner member 11 which is a large-diameter portion of an input shaft 1 x .
  • the inner member 11 has a radially outer raceway 15 a .
  • the outer ring 14 is provided around the raceway 15 a and is formed with cam surfaces 16 a on its inner periphery.
  • a retainer 12 having a plurality of pockets 17 is disposed between the inner member 11 and the outer ring 14 .
  • As many rollers 13 as the number of cam surfaces 16 a are respectively received in the pockets 17 and circumferentially equidistantly spaced apart from each other by the retainer 12 .
  • the retainer 12 is connected to the outer ring 14 through a switch spring 18 so as to be rotatable relative to the outer ring 14 .
  • the switch spring 18 biases the retainer 12 relative to the outer ring 14 toward a neutral position where each roller 13 is received in a recess defined between a pair of adjacent cam surfaces 16 a.
  • the switch spring 18 is a ring-shaped member provided along the inner periphery of the retainer 12 near its end adjacent to the electromagnetic clutch unit.
  • the switch spring 18 has radially outwardly bent end portions 18 a that are received in cutouts 12 c and 14 c formed in the retainer 12 and the outer ring 14 , respectively, thereby biasing the retainer 12 toward a position where the cutouts 12 c and 14 c radially align with each other.
  • the outer ring 14 has an integral extension 5 at its end remote from the electromagnetic clutch unit 20 .
  • the rotation transmission device of this embodiment further includes a gear 6 through which torque is transferred to an external element from the outer ring 14 , and a gear 7 through which torque is transferred to the input shaft 1 x from an external member.
  • the electromagnetic clutch unit 20 comprises a rotor 22 fixed to the input shaft 1 x through a sleeve 19 and having a flange 22 a , an electromagnetic coil 21 disposed on one side of the flange 22 a , and an armature 23 disposed on the other side of the flange 22 a .
  • the armature 23 is mounted on the sleeve 19 through a friction-reducing member 19 a so as to be rotatable and axially movable within a predetermined distance relative to the sleeve 19 .
  • the armature 23 is formed with a plurality of holes in which projections formed on the end surface of the retainer 12 are respectively inserted. The armature 23 is thus rotationally fixed to the retainer 12 .
  • the armature 23 is pulled toward roller clutch unit 10 by a separation spring 24 secured to the outer ring 14 .
  • the armature 23 which is axially movable relative to the retainer 12 , is brought into frictional contact with the flange 22 a of the rotor 22 . Because the rotor 22 is fixed to the input shaft 1 x , while the armature 23 is rotationally fixed to the retainer 12 , with the rotation of the input shaft 1 x , the retainer 12 rotates relative to the outer ring 14 against the force of the switch spring 18 , thereby pushing each roller 13 into one of the narrow ends of the wedge-shaped space. Torque is thus transferred from the inner member 11 to the outer ring 14 .
  • FIG. 5 shows a control circuit that can be used for either of the inner cam type and outer cam type and that can variably and optimally set the current, thereby reducing the power consumption compared to conventional pulse width modulation (PWM) control.
  • PWM pulse width modulation
  • the control circuit of FIG. 5 includes an electronic control unit (ECU) 30 in the form of a microcomputer which receives signals indicating the revolving speeds of the input shaft 1 x and the output shaft 5 x from rotation sensors 34 a and 34 b mounted on the shafts 1 x and 5 x , respectively, and based on these signals, controls the current applied to the electromagnetic coil 21 from the vehicle battery (power source) 30 B through a variable setting unit 32 or a PWM unit 33 .
  • the variable setting unit 32 sets the current to the electromagnetic coil 21 , when the clutch is engaged, to an optimum value based on the revolving speeds of the input shaft 1 x and the output shaft 5 x .
  • the PWM unit 33 intermittently applies current to the electromagnetic coil 21 by PWM control to keep the clutch unit 20 engaged.
  • the control circuit further includes an input switch SW 31 for selectively turning on and off a mode switch 35 to be described below.
  • the control circuit operates differently for the inner cam type and the outer cam type to control the engagement of the electromagnetic clutch unit 20 .
  • the rollers 13 are moved radially outwardly and pressed against the raceway 16 of the outer ring 14 under centrifugal force.
  • the frictional force therebetween therefore serves to slow down the revolving speed of the rollers 13 about the axis of the input shaft, thus assisting in the engagement of the clutch.
  • FIG. 6A shows the current I variably applied to the electromagnetic coil 21 by the variable setting unit 32 according to the revolving speed N of the inner member 11
  • FIG. 6B shows the relationship between the clearance ⁇ between the rotor 22 and the armature 23 determined based on the variably set current I and the magnetic attraction force F necessary to engage the clutch with revolving speeds N X , N Y and N Z as parameters.
  • the inner member 11 is referred to as the cam ring.
  • Symbols N 0 and I 0 in FIG. 6A indicate the rated revolving speed and the rated current, respectively, which are described later.
  • FIGS. 7A and 7B correspond to FIGS. 6A and 6B , respectively, for the outer cam type except that the horizontal axis in FIG. 7A indicates not the revolving speed of the cam ring but the revolving speed N of the outer ring.
  • FIG. 7B with an increase in revolving speed of the outer ring 14 , greater centrifugal force acts on the rollers 13 .
  • the rollers 13 are received in the recesses defined between the adjacent cam surfaces 16 a .
  • the current I necessary to be applied to the electromagnetic coil 21 to engage the clutch is large. Also as shown in FIG.
  • the current applied to the electromagnetic coil 21 is controlled by PWM irrespectively of the revolving speed so that the frictional torque of the armature is greater than the torque for keeping the clutch in the neutral position.
  • the applied current is controlled to a maximum value with reference to the expected maximum value of the revolving speed N of the inner member or the outer ring.
  • the current I applied to the electromagnetic coil 21 is variably controlled based on the revolving speed N and depending on whether the rotation transmission device is of the inner cam type or the outer cam type.
  • This makes it possible to reduce the applied current in the revolving speed range where an unnecessarily large current was applied in the prior art, which in turn makes it possible to further save energy and reduce the size of the electromagnetic coil 21 compared to the conventional control arrangement.
  • the control unit 30 receives signals from the rotation sensors 34 a and 34 b mounted on the input and output shafts 1 x and 5 x , respectively, and controls the applied current based on such signals.
  • the applied current is preferably controlled such that the response of the clutch improves simultaneously.
  • it is necessary to shorten the duration of each of the steps when the clutch engages i.e. the steps of (1) applying current to the electromagnetic coil 21 , (2) attracting the armature 23 , which is spaced from the rotor 22 through the clearance ⁇ , to the rotor 22 , and (3) producing torque necessary to push the rollers 13 into narrow ends of the wedge-shaped spaces defined between the inner member 11 and the outer ring 14 by the contact between the rotor and the armature.
  • FIGS. 8A and 8B are graphs showing a control method for shortening the durations of the steps (1) and (2).
  • FIG. 8A shows, three-dimensionally, the relationship between the applied current I, the revolving speed N and time t.
  • FIG. 8B shows, two-dimensionally, the relationship between the applied current I 0 and time t 0 when the revolving speed is a predetermined value, e.g. the rated value N 0 .
  • These graphs show the control method for the outer cam type.
  • the applied current is variably controlled to engage the clutch.
  • the control for improving the response of the clutch is carried out by means of the variable setting unit 32 by applying current nI 0 that is greater by a factor of n (n>1) than the reference current N 0 , which is a minimum value necessary to engage the clutch when the shaft is rotating at N 0 , during the period from when the electromagnetic coil 21 is energized until the clutch engages (time t 0 ), and after the clutch has engaged at time t 0 , reducing the applied current to the reference current I 0 .
  • the revolving speed N is not equal to the rated revolving speed N 0 , this control is carried out in the same manner based on the current revolving speed N as shown in FIG. 8A .
  • the control unit 30 compares the signals from the rotation sensors 34 a and 34 b . If they are identical or substantially identical (to a predetermined degree) to each other, the control unit 30 determines that the electromagnetic clutch unit 20 has completely engaged, and reduces the applied current from nI 0 to I 0 through the variable setting unit 32 . After the applied current has been reduced to I 0 , the PWM unit 33 performs the PWM control to intermittently apply current.
  • the rated revolving speed N 0 is determined taking into consideration the factors mentioned below, and the size of the electromagnetic coil 21 is determined based on the current value I 0 corresponding to the rated revolving speed N 0 . This makes it possible to minimize the size of the electromagnetic coil 21 .
  • FIG. 9 shows the relationship between the revolving speed N and the frequency of use of the clutch (the number of times the clutch is turned on and off) when a clutch of the outer cam type as the rotation transmission device is mounted on the drivetrain of a vehicle.
  • the rated revolving speed N 0 is the revolving speed at which the frequency of use of the clutch is at a maximum.
  • the rated revolving speed N 0 is a speed which is lower than the average of the maximum and minimum revolving speeds.
  • the size of the electromagnetic coil is determined based on the rated revolving speed.
  • the rotation transmission device is used in a high revolving speed range or in a low revolving speed range.
  • the rated revolving speed is determined taking into consideration such intended use, and the size of the electromagnetic coil is determined based on the rated revolving speed. But in actual use conditions, as shown in FIG. 8A , the clutch may be engaged while the revolving speed is lower or higher than the rated revolving speed N 0 . If the clutch engages while the revolving speed is higher than N 0 , a relatively large current is applied to the coil. But at such a high revolving speed, the clutch is engaged less or least frequently, so that this will have no significant influence on the life span and durability of the electromagnetic coil. Such use is appropriate because the size of the electromagnetic coil is determined taking into consideration the frequency of use.
  • the current I 0 is a value after the engagement of the clutch when the inner member 11 or the outer ring 14 is rotating at a revolving speed N when it engages, and changes with the actual revolving speed N.
  • FIGS. 10A and 10B schematically show a mode switching circuit including the mode switch 35 for the electromagnetic coil 21 provided in a power supply line Lc.
  • the mode switching circuit can be used as a heater for producing heat in a low temperature environment to prevent erroneous engagement of the clutch.
  • FIG. 10A shows a heating mode.
  • FIG. 10B shows the electromagnetic coil 21 used in the drive mode.
  • the mode switching circuit includes a central line Lcn connected to the center of the electromagnetic coil 21 to divide the coil into two portions 21 X and 21 Y so that the heating mode and the drive mode can be changed over by the mode switch 35 . It is also possible to prevent erroneous engagement.
  • the mode switch 35 has two switches 35 a and 35 b in lines Lc+ and Lcn connected to the positive side and the central position of the power supply line Lc.
  • the line Lc+ is bifurcated so as to be connectable to one of the two switches 35 a and 35 b .
  • Line Lc ⁇ is grounded.
  • the two switches 35 a and 35 b are provided at least downstream of the variable setting unit 32 . While not shown, if the PWM unit 33 is provided, they are preferably provided downstream of the PWM unit too. While not shown, the modes are changed over by applying control signals to the two switches 35 a and 35 b from the control unit 30 .
  • Numeral 30 B is the vehicle battery (power source).
  • the heating mode of FIG. 10A is selected when the vehicle is started at low temperature, because the switch 35 a of the mode switch 35 is connected to Lc+ and the switch 35 b is connected to Lcn, the current from the power source 30 B flows partially through the coil 21 X and partially through the coil 21 Y .
  • the magnetic fluxes ⁇ X and ⁇ Y produced in the coils 21 X and 21 Y are opposite in direction from each other and cancel each other, so that the electromagnetic coil 21 produces no magnetic attraction and produces only heat as a heater. If the drive mode in FIG.
  • the switch 35 a is separated from line Lc+ and the switch 35 b is connected to line Lc+ (and separated from line Lcn), so that the two electromagnetic coils 21 X and 21 Y act as the single electromagnetic coil 21 to produce magnetic flux ⁇ , which in turn produces magnetic attraction.
  • FIG. 11 shows a partial sectional view of the rotation transmission device of the third embodiment, which is of the inner cam type.
  • the rotation transmission device of this embodiment is substantially identical in structure to the embodiment of FIG. 1 . But in this embodiment, details of the rotation transmission device are improved, which are missing in FIG. 1 and its description.
  • the output member comprises an outer ring and a separate nonmagnetic cover to reduce the weight of the rotation transmission device and to provide more secure coupling of the cover to the outer ring.
  • some of the elements identical or corresponding to elements of FIG. 1 are identified by different names and by the same numerals with a prime (′) added thereto. (The names used in the embodiment of FIG. 1 are shown in brackets.)
  • the input member 1 ′ includes a large-diameter portion 11 a ′ (inner member 11 ) having at its front end a stepped shaft portion 11 b ′.
  • the output member 5 ′ (output shaft 5 x ) is provided around the large-diameter portion 11 a ′.
  • the output member 5 ′ comprises an outer ring 14 ′ (outer ring 14 ) and a separate cover 22 g ′ (rotor guide 22 g ).
  • the outer ring 14 ′ is made of a metal and has a bearing fitting surface 16 a ′ on its inner periphery.
  • a bearing 4 ′ (bearing 4 ) is disposed between the bearing fitting surface 16 a ′ and the shaft portion 11 b ′ so that the input member 1 ′ and the outer ring 14 ′ are rotatable relative to each other.
  • the outer ring 14 ′ has at its open end first and second cylindrical portions 14 a ′ and 14 b ′ that are disposed axially displaced from each other.
  • the first cylindrical portion 14 a ′ has a larger inner diameter than the second cylindrical portion 14 b ′.
  • the cover 22 g ′ is made of a nonmagnetic material such as synthetic resin and is inserted in the first cylindrical portion 14 a ′.
  • the cover 22 g ′ has an outer diameter substantially equal to the inner diameter of the first cylindrical portion 14 a ′.
  • the cover 22 g ′ has at its end facing the outer ring 14 ′ a plurality of protrusions 28 ′ that are circumferentially spaced apart from each other at equal intervals and fitted in cutouts 29 ′ formed in the first and second cylindrical portions 14 a ′ and 14 b ′, thereby preventing the cover 22 g ′ from rotating relative to the outer ring 14 ′.
  • the protrusions 28 ′ have a smaller axial length than the second cylindrical portion 14 b ′, thereby defining discharge holes 27 ′ for lubricating oil between the opposed end surfaces of the protrusions 28 ′ and the cutouts 29 ′.
  • a snap ring 26 ′ is received in circumferentially aligned ring grooves 26 a ′ formed in the inner peripheral surfaces of the protrusions 28 ′ and the second cylindrical portion 14 b ′ to prevent axial separation of the cover 22 g ′ from the outer ring 14 ′.
  • a two-way roller clutch 10 ′ is mounted to selectively couple and uncouple the members 1 ′ and 14 ′.
  • the two-way clutch 10 ′ includes a plurality of engaging elements 13 ′ (rollers 13 ) in the form of rollers disposed between a cylindrical surface 16 ′ (raceway 16 ) formed on the inner periphery of the outer ring 14 ′ and having the same diameter as the bearing fitting surface 16 a ′ and a plurality of cam surfaces 15 ′ (cam surfaces 15 ) formed on the outer periphery of the large-diameter portion 11 a ′ of the input member 1 ′ and defining wedge-shaped spaces between the cam surfaces and the cylindrical surface 16 ′.
  • rollers 13 rollers in the form of rollers disposed between a cylindrical surface 16 ′ (raceway 16 ) formed on the inner periphery of the outer ring 14 ′ and having the same diameter as the bearing fitting surface 16 a ′ and a plurality of cam surfaces 15 ′ (cam surfaces 15 ) formed on the outer periphery of the large-diameter portion 11 a ′ of the input member 1 ′ and defining wedge-
  • the engaging elements 13 ′ are retained by a retainer 12 ′ (retainer 12 ) mounted between the large-diameter portion 11 a ′ and the outer ring 14 ′.
  • a retainer 12 ′ (retainer 12 ) mounted between the large-diameter portion 11 a ′ and the outer ring 14 ′.
  • a recess 11 ar ′ is formed in the end surface of the large-diameter portion 11 a ′.
  • a ring groove 11 ag ′ (groove 11 a ) is formed in the inner surface of the peripheral wall defining the recess 11 ar ′.
  • a C-shaped switch spring 18 ′ (switch spring 18 ) is received in the ring groove 11 ag ′.
  • the switch spring 18 ′ has radially outwardly bent end portions 18 a ′ (end portions 18 a ) that are inserted through a cutout 11 c ′ (cutout 11 c ) formed in the peripheral wall defining the recess 11 ar ′ and a cutout 12 c ′ (cutout 12 c ) formed in the end surface of the retainer 12 ′, thereby biasing the circumferentially opposed ends of the respective cutouts 11 c ′ and 12 c ′ in directions away from each other and biasing the retainer 12 ′ toward a neutral position where the engaging elements 13 ′ disengage from the cylindrical surface 16 ′ and the cam surfaces 15 ′.
  • the retainer 12 ′ has a radially inwardly extending flange 12 a ′ at its front end which is rotatably supported on a large-diameter portion 11 c ′ of the stepped shaft portion 11 b ′.
  • a snap ring 11 r ′ is fitted in a ring groove 11 bg ′ formed in the outer periphery of the large-diameter portion 11 a ′.
  • the snap ring 11 r ′ rotatably supports the inner periphery of the retainer 12 ′ near its rear end.
  • the ring groove 11 ag ′ in which the switch spring 18 ′ is received has such a depth that the switch spring 18 ′ does not come out of the groove 11 ag ′ when the spring 18 ′ is compressed to its limit.
  • an electromagnetic clutch 20 ′ (electromagnetic clutch 20 ) is disposed between the input member 1 ′ and the cover 22 g ′ to selectively engage and disengage the two-way clutch 10 ′.
  • the electromagnetic clutch 20 ′ comprises an armature 23 ′ (armature 23 ) axially facing the retainer 12 ′, a rotor 22 ′ (rotor 22 ) axially facing the armature 23 ′, an electromagnet 21 M ′ axially facing the rotor 22 ′, and a separation spring 24 ′ (separation spring 24 ) biasing the armature 23 ′ away from the rotor 22 ′.
  • the armature 23 ′ has a plurality of holes 23 a ′ in which protrusions 23 b ′ formed on the end surface of the retainer 12 ′ are received so that the armature 23 ′ is rotationally fixed but axially movable relative to the retainer 12 ′.
  • the rotor 22 ′ includes an outer cylindrical portion 22 a ′ and an inner cylindrical portion 22 b ′.
  • the outer cylindrical portion 22 a ′ is pressed into and rotationally fixed to the cover 22 g ′. Also, its axial movement is prevented by a snap ring 22 c ′ secured to the inner periphery of the cover 22 g ′ at its rear end.
  • a sleeve 3 a ′ made of a nonmagnetic material is pressed into the inner cylindrical portion 22 b ′.
  • the rotor 22 ′ is rotatably supported on the input member 1 ′ through a bearing 3 ′ (bearing 3 ) disposed between the sleeve 3 a ′ and the input member 1 ′.
  • a seal member 3 s ′ is also disposed between the sleeve 3 a ′ and the input member 1 ′ to prevent the entry of foreign matter.
  • the rotor 22 ′ is formed with a plurality of arcuate slits 23 s ′ defining a circle in its portion facing the armature 23 ′.
  • An elastic member 23 e ′ made of a nonmagnetic material is fitted in each slit 23 s ′.
  • the elastic members 23 e ′ prevent the entry of foreign matter through the slits 23 s ′.
  • the elastic members 23 e ′ axially protrude from the surface of the rotor 22 ′ facing the armature 23 ′ (and adapted to be magnetically attracted to the armature). With this arrangement, it is possible to omit the separation spring 24 ′.
  • the electromagnet 21 M ′ is disposed between the outer and inner cylindrical portions 22 a ′ and 22 b ′ of the rotor 22 ′.
  • the electromagnet 21 M ′ includes an electromagnetic coil 21 ′ (electromagnetic coil 21 ). By energizing the electromagnetic coil 21 ′, the armature 23 ′ is attracted to the rotor 22 ′.
  • the electromagnet 21 M ′ is supported on a support plate Sp, which is in turn supported on an outer ring 2 a ′ of a bearing 2 ′ rotatably supporting the input member 1 ′.
  • By supporting the electromagnet 21 M ′ on the outer ring 2 a ′ of the bearing 2 ′ it is possible to support the electromagnet 21 M ′ so as to be coaxial with the input member 1 ′ with high accuracy.
  • the support plate Sp has an arm Spa extending from its radially outer edge and having its free end screwed to a stationary member B.
  • the arm Spa is formed with a slit Spb in which a lead wire Lc of the electromagnetic coil 21 ′ is received and fixed to the arm e.g. by means of an adhesive or by molding with a synthetic resin.
  • the input member 1 ′ has an oil supply passage 60 having an inlet 60 a at the end surface of the input member 1 ′.
  • Lubricating oil supplied into the oil supply passage 60 from its inlet 60 a flows into the bearing 3 ′ supporting the sleeve 3 a ′ to lubricate the bearing 3 ′, and flows through the gap between the sleeve 3 a ′ and the input member 1 ′ to lubricate the opposed surfaces of the armature 23 ′ and the rotor 22 ′ and the two-way roller clutch 10 ′.
  • a filter 61 is mounted in the inlet 60 a to catch any foreign matter contained in lubricant.
  • the switch spring 18 ′ When the input member 1 ′ and the retainer 12 ′ rotate relative to each other, the switch spring 18 ′ is elastically deformed, i.e. radially compressed. But because the ring groove 11 ag ′ has a depth sufficient to retain the switch spring 18 ′ in position even when the switch spring 18 ′ is radially compressed to a maximum degree, the switch spring 18 ′ n ever comes out of the ring groove 11 ag ′.
  • the electromagnetic coil 21 ′ When the electromagnetic coil 21 ′ is deenergized, the retainer 12 ′ rotates under the force of the switch spring 18 ′ back to the neutral position where the engaging elements 13 ′ disengage from the cylindrical surface 16 ′ and the cam surfaces 15 ′.
  • the cover 22 g ′ is coupled to the open end of the outer ring 14 ′ to support the rotor 22 ′, and the cover 22 g ′ is made of a nonmagnetic material, it is possible to reduce the axial length of the outer ring 14 ′ to such a degree as to be able to barely cover the two-way roller clutch 10 ′. This in turn makes it possible to reduce the weight of the rotation transmission device.
  • the protrusions 28 ′ formed on the end surface of the cover 22 g ′ are engaged in the cutouts 29 ′ formed in the first and second cylindrical portions 14 a ′ and 14 b ′ of the outer ring 14 ′ to rotationally fix the cover 22 g ′, and the protrusions 28 ′ and the second cylindrical portion 14 b ′ are axially coupled together by the snap ring 26 ′ fitted on the radially inner surface of the second cylindrical surface 14 b ′, even when the output member 5 ′ rotates at high speed, it is possible to reliably prevent separation of the snap ring 26 ′ and thus the cover.
  • the discharge holes 27 ′ formed between the protrusions 28 ′ and the cutouts 29 ′ eliminate the need to form discharge holes later. This leads to a reduction in the machining cost of the outer ring 14 ′ or the cover 22 g ′.
  • a valve body 63 that opens under centrifugal force produced when the outer ring 14 ′ rotates is preferably mounted in the discharge hole 62 to prevent the entry of foreign matter through the discharge hole 62 while the output member 5 ′ is not rotating by closing the discharge hole 62 with the valve body 63 .
  • the valve body 63 is a spherical member pressed by a tension spring 65 against a conical seating surface 64 formed on the radially outer end of the discharge hole 62 so as to be separable from the seating surface 64 against the force of the spring 65 .
  • the valve body 63 comprises two elastic members 63 a and 63 b mounted in the discharge hole 62 .
  • the elastic members 63 a and 63 b are normally in elastic contact with each other to prevent the entry of foreign matter. Under centrifugal force produced when the outer ring rotates or due to an increase in the internal pressure, the elastic members 63 a and 63 b separate from each other, allowing lubricating oil to be discharged through the gap therebetween.
  • the elastic members 23 e ′ serve to separate the armature 23 ′ from the rotor 22 ′. This eliminates the need for the separation spring 24 ′ shown in FIG. 14 , thus reducing the cost. Also as shown in FIG. 15 , by mounting the elastic members 23 e ′ in the slits 23 s ′ formed in the rotor 22 ′ so that the elastic members 23 e ′ protrude from the surface of the rotor 22 ′ facing the armature 23 ′, the elastic members 23 e ′ serve to separate the armature 23 ′ from the rotor 22 ′. This eliminates the need for the separation spring 24 ′ shown in FIG. 14 , thus reducing the cost. Also as shown in FIG.
  • the inner periphery of the outer ring 14 ′ can be machined easily, so that it is possible to reduce the machining cost.
  • the cylindrical surface 16 ′ is formed on the inner periphery of the outer ring 14 ′, and the cam surfaces 15 ′ are formed on the outer periphery of the large-diameter portion 11 a ′.
  • cam surfaces may be formed on the inner periphery of the outer ring 14 ′, and a cylindrical surface may be formed on the outer periphery of the large-diameter portion.
  • the outer ring 14 ′ and the retainer 12 ′ are coupled together through the switch spring for keeping the engaging elements 13 ′ in neutral position, and the rotor 22 ′ of the electromagnetic clutch 20 is rotationally fixed to the input member 1 ′.
  • the concept of the invention is applicable to various rotation transmission devices of the type in which its roller clutch is selectively engaged and disengaged by electromagnetic force.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
  • Arrangement And Mounting Of Devices That Control Transmission Of Motive Force (AREA)
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JP2004-057567 2004-03-02
JP2004057567A JP4545457B2 (ja) 2004-03-02 2004-03-02 回転伝達装置
JP2004-195769 2004-07-01
JP2004195769A JP4824288B2 (ja) 2004-07-01 2004-07-01 回転伝達装置
PCT/JP2005/003516 WO2005083287A1 (ja) 2004-03-02 2005-03-02 回転伝達装置

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JP7262174B2 (ja) 2018-03-26 2023-04-21 Ntn株式会社 回転制動装置
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US20070170029A1 (en) 2007-07-26
EP1722120A1 (de) 2006-11-15
WO2005083287A1 (ja) 2005-09-09

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